Soundboard

ABSTRACT

A soundboard for musical instruments and sound systems for improving tone quality and balance in resonance over a wide range of pitch. The soundboard has sound bars spirally or convolutely arranged, that is, in a fashion such that the inner ends of a plurality of bars are tangent to a circle at a suitable position on the soundboard and the other ends of the bars are fixed to the edge frame of the soundboard. The effect of the spiral arrangement of sound bars is further improved by providing an annular rib at the center of the spirally arranged sound bars so that the rib secures the ends of the bars onto the soundboard. The effect is still further improved by providing one or more tunnel-like channels in the part of the annular rib that contacts the soundboard.

United States Patent Yamamoto 1 Aug. 29, 1972 1 SOUNDBOARD Prima Examiner-Richard B. Wilkinson 72 I t Yamam t 1 W Y 1 men or g ggl g i g 232: Assistant Examiner-Lawrence R. Franklin p Attorney-Wenderoth, Lind & Ponack [22] Filed: Sept. 17, 1970 [57] ABSTRACT [21] Appl. No.: 73,019 A soundboard for musical instruments and sound systems for improving tone quality and balance in resonance over a wide range of pitch. The soundboard [30] Forelgn Apphcaton Pnonty Data has sound bars spirally or convolutely arranged, that Sept. 22, 1969 Japan ..44/75386 in a fashi n su h that the inner ends of a plurality of bars are tangent to a circle at a suitable position on [52] U.S. Cl ..84/195 the Soundboard and the ether ends of the bets are 51 Int. Cl. ..Gl0c 3/06 fixed to the edge frame of the Seuhdheem The effect 58 Field at Search ..84/189, 192, 19s of the Spiral arrangement of Sound bets is further proved by providing an annular rib at the center of the 56 R f C-ted spirally arranged sound bars so that the rib secures the 1 e erences l ends of the bars onto the soundboard. The effect is UNITED STATES PATENTS still further im roved b rovidin one or more tun- P Y P g 582 577 5/1897 Bruenn 84/195 nel-like channels in the part of the annular rib that I I I e e I e e ta ts m d- 1,052,755 2/1913 S'chmitt et a1 ..84/195 c 6 Oar 1,893,893 1/1933 Hammond ..84/192 X 12 Claims, 7 Drawing Figures PATENTEDAUGZSJ IZ SHEEI 1 0F 2 KINYA YAMAMOTO',

1 INVENTOR BYMMM $1M ATTORNEY s PKTENTEDmzsmn 3,688,011

sum 2 or 2 KI NYA YAMAMOTO mvsmon BMLAM 54 GMIM ATTORNEY S SOUNDBOARD BACKGROUND OF THE INVENTION This invention relates to a soundboard for use in musical instruments and sound systems. It is well known to use a soundboard for a stringed instrument such as a piano or guitar or a sound system such as a speaker box or a receiving set cabinet, etc. in order to create a resonance effect. It is also well known to secure bars or ribs vonto said soundboard in order to improve the resonance effect.

The conventional piano soundboard has oblique parallel bars. It has been proposed that the sound bars be placed radially. But such sound bar arrangements of the prior art do not give a well-balanced resonance effect over a wide range of pitch.

A soundboard made of wood is characterized in that sound vibration is propagated along the straight grain of the wood material. I have searched for a new resonance board structure, making it a principle of my study to make use of the above mentioned characteristic of the propagation of sound in the wood material and to oppress the free vibration of the soundboard as little as possible, and as a result of this search have made this invention.

SUMMARY OF THE INVENTION The invention of this application comprises'securing sound bars onto a soundboard in an arrangement in which a plurality of bars are placed spirally or convolutely, that is, the inner ends of the bars are tangent to a circle at a suitable position on the soundboard and with bars tangent to diametrally opposite points being parallel. By this arrangement, a well-balanced resonance effect is produced.

In one embodiment of this invention, an annular rib is fixed over the circle formed by the inner ends of the spirally arranged sound bars so that said annular rib fixes said ends. This contributes to a further improvement of the above-mentioned effect and a better fixation of the sound bars.

In still another embodiment of this invention, at least one, and preferably, several, tunnel-like channels are provided in the part of said annular rib that contacts the soundboard. By this means, dulling or damping of tones of higher pitch which is observed when the above-mentioned annular rib is employed is eliminated.

The board, bars and rib are usually made of wood, but the material is not necessarily limited thereto. Metal, polymer material, plarnowood, etc. can be used.

The soundboard of this invention can be used for all kinds of musical instruments and sound systems. The effect of the soundboard is especially remarkable when it is used for a keyed instrument such as a piano or harpsichord, a stringed instrument such as guitar, and sound systems such as a speaker box or a receiving set cabinet.

BRIEF EXPLANATION OF THE DRAWINGS FIG. 1 (a) is a plan view of a soundboard which is an embodiment of this invention. FIG. 1 (b) is a sectional view along section line (X-X) in FIG. 1 (a).

FIG. 2 (a) is a plan view of a soundboard which is another embodiment of this invention. FIG. 2 (b) is a sectional view along line X X in FIG. 2 (a) and FIG. 2 (c) is a sectional view along line Y Y in FIG. 2 (a).

FIG. 3 (a) is a plan view of a soundboard representing still another embodiment of this invention. FIG. 3 (b) is a sectional view on line X-X of FIG. 3 a showing the annular rib in which through-holes or tunnel-like channels are provided.

DETAILED DESCRIPTION OF THE INVENTION The invention will be explained in detail with reference to the attached drawings.

In the drawings, 1 represents a soundboard, 2 is an edge frame, 3 is a bridge for middle and high pitch ranges, 4 is a bridge for the low pitch range, 5 is an an nular rib, and 6 designates sound bars, 7 is the connection of the edge frame 2 and bars 6, 8 designates the ends of the bars, and in FIG. 2 and 3, the connection of annular rib 5 and bar 6, and 9 is a small tunnel-like hole provided in annular rib 5.

In the embodiment of this invention pertaining to the soundboard shown in FIG. 1, which is for a piano sound, bars are arranged spirally with the inner ends 8 thereof tangential to a circle at a suitable position on the soundboard. The circle may be positioned in the high pitch tone resonance region, middle pitch tone resonance region or low pitch tone resonance region of the soundboard.

The other end of each bar is fixed to the edge frame of the soundboard.

The bars are arranged spirally so that the inner ends thereof are tangential to a circle, and bars are tangent to diametrally opposite points on the circle so that they are substantially parallel to each other. Therefore, rigidity of the soundboard as a whole is decreased and thus its free vibration is increased as well as in the radial arrangement. But because there are pairs of parallel bars, the degree of localization or centralization of the antinode or loop of vibration at said circle as observed in the radial arrangement, is decreased. Thus this arrangement of bars give an increased and better balanced resonance effect.

In this embodiment, bridges are employed in combination with the sound bars. In FIG. 1, the bars are spirally arranged so that the circle formed by the inner ends thereof is placed at one end of the middle and high pitch range bridge. But positions of the circle and the bridges can be selected at the manufacturers discretion or the players preference. The circle may be placed at a position bridging a low pitch range bridge and a high and middle pitch range bridge. Use of the bridge is a known technique and there is no necessity to explain this in detail.

The effect of the spiral arrangement of the sound bars is shown by the following facts. The logarithmic decrement of vibration at the characteristic frequency of the soundboard of the above described embodiment of this invention is 2.3, and it takes 3.5 seconds to be clamped to 60db. In contrast, the logarithmic decrement of vibration at the characteristic frequency of the conventional soundboard of the prior art is 2.0, and it takes 3.0 seconds to be damped to 60db.

The characteristic frequency of the soundboard of the above embodiment of this invention is ISI-Iz while that of the soundboard of the prior art is 24Hz.

This embodiment of the invention can be successfully applied to a guitar and a speaker box. A plurality of sound bars are secured in the spiral or convolute arrangement on the inside surface of the guitar chest soundboard having a sound hole. In this case sound bars are secured to the board by means of an adhesive and no joinery work is employed for fixation of the ends of the bars. Increased and better-balanced resonance was effected in this case, too. When this arrangement of sound bars is applied to a speaker box, the same effect is achieved.

In another embodiment of this invention as shown in FIGS. 2a 2c, an annular rib is secured at the circle formed by the inner ends of the sound bars so that the rib fixes the free ends of the bars. The shape of the annular rib need not necessarily be a true circle, but it may be an ellipse or any other modified form.

In this embodiment, as shown in FIGS. 2a 2c, bridges are used in combination with the bars and the annular rib. The circle is placed at the same position as in FIG. 1.

In this embodiment of the invention, the localization of the vibration antinode or loop is further decreased and therefore balance of resonance is further improved, and better fixation of the ends of the bars to the soundboard is secured.

However, when the resonance of each sound is closely investigated, it is noticed that some tones of higher pitch are damped. I have found this defect is markedly decreased by providing one or more, usually several, tunnel-like channels in the part of said annular rib which contacts the soundboard.

This feature is shown in FIGS. 3a and 3b. This specific embodiment corresponds to the embodiment of FIGS. 2a 2c and the general structure is substantially the same as the latter. Only as seen inFIGS. 3a and 3b, tunnel-like channels 9 are provided in the annular rib. All the other aspects explained with respect to the embodiment of FIGS. 2a 2c are applicable to this embodiment, too.

The size, configuration and number of the tunnellike channels can be modified over a wide range in accordance with the manufacturers discretion and/or the players preference.

Adhesion of the board and the bar or rib, and joinery work between the ends of the bars and the rib or the edge frame are well known to those skilled in the art and there is no necessity to explain them in detail.

What I claim is:

1. An improved soundboard, comprising a soundboard and a plurality of straight sound bars secured on said sound board, said sound bars being arranged in a spiral arrangement with the inner ends of the bars being tangent to a circle.

2. An improved soundboard as claimed in claim 1 in which pairs of said sound bars are tangent to the circle at diametrally opposite points on the circle and are substantially parallel to each other.

3. An improved soundboard as claimed in claim 1 further comprising at least one bridge on said soundboard.

4. An improved soundboard as claimed in claim 3 in which there are a plurality of bridges on said soundboard, a low pitch range and a high and middle pitch range bridge, the circle on which the ends of the sound bars lie being at one end of the high and middle pitch range bridge.

5. An improved soundboard, comprising a soundboard and l alit of st ai ht so n bars secur d on said soundg ai' d, said sou nd bars bei ng arrangeti in a spiral arrangement with the inner ends of the bars being tangent to a circle, and an annular rib overlying the inner ends of the soundbars and secured to said soundboard for fixing the inner ends of the soundbars to the soundboard.

6. An improved soundboard as claimed in claim 5 in which pairs of said soundbars are tangent to the circle at diametrally opposite points on the circle and are substantially parallel to each other.

7. An improved soundboard as claimed in claim 5 further comprising at least one bridge on said soundboard.

8. An improved soundboard as claimed in claim 7 in which there are two bridges and said circle is positioned between said bridges.

9. An improved soundboard comprising a soundboard and a plurality of straight sound bars secured on said soundboard, said sound bars being arranged in a spiral arrangement with the inner ends of the bars being tangent to a circle, and an annular rib overlying the inner ends of the soundbars and secured to said soundboard for fixing the inner ends of the soundbars to the soundboard, said annular rib having at least one tunnellike channel therethrough extending through a part thereof which contacts the soundboard between the ends of said soundbars.

10. An improved soundboard as claimed in claim 9 in which pairs of said soundbars are tangent to the circle at diametrally opposite points on the circle and are substantially parallel to each other.

11. An improved soundboard as claimed in claim 9 further comprising at least one bridge on said soundboard.

12. An improved soundboard as claimed in claim 11 in which there are two bridges and said circle is positioned between said two bridges. 

1. An improved soundboard, comprising a soundboard and a plurality of straight sound bars secured on said sound board, said sound bars being arranged in a spiral arrangement with the inner ends of the bars being tangent to a circle.
 2. An improved soundboard as claimed in claim 1 in which pairs of said sound bars are tangent to the circle at diametrally opposite points on the circle and are substantially parallel to each other.
 3. An improved soundboard as claimed in claim 1 further comprising at least one bridge on said soundboard.
 4. An improved soundboard as claimed in claim 3 in which there are a plurality of bridges on said soundboard, a low pitch range and a high and middle pitch range bridge, the circle on which the ends of the sound bars lie being at one end of the high and middle pitch range bridge.
 5. An improved soundboard, comprising a soundboard and a plurality of straight sound bars secured on said soundboard, said sound bars being arranged in a spiral arrangement with the inner ends of the bars being tangent to a circle, and an annular rib overlying the inner ends of the soundbars and secured to said soundboard for fixing the inner ends of the soundbars to the soundboard.
 6. An improved soundboard as claimed in claim 5 in which pairs of said soundbars are tangent to the circle at diametrally opposite points on the circle and are substantially parallel to each other.
 7. An improved soundboard as claimed in claim 5 further comprising at least one bridge on said soundboard.
 8. An improved soundboard as claimed in claim 7 in which there are two bridges and said circle is positioned between said bridges.
 9. An improved soundboard comprising a soundboard and a plurality of straight sound bars secured on said soundboard, said sound bars being arranged in a spiral arrangement with the inner ends of the bars being tangent to a circle, and an annular rib overlying the inner ends of the soundbars and secured to said soundboard for fixing the inner ends of the soundbars to the soundboard, said annular rib having at least one tunnel-like channel therethrough extending through a part thereof which contacts the soundboard between the ends of said soundbars.
 10. An improved soundboard as claimed in claim 9 in which pairs of said soundbars are tangent to the circle at diametrally opposite points on the circle and are substantially parallel to each other.
 11. An improved soundboard as claimed in claim 9 further comprising at least one bridge on said soundboard.
 12. An improved soundboard as claimed in claim 11 in which there are two bridges and said circle is positioned between said two bridges. 